Method of and means for adjusting flow rates of fluids through formations traversed by boreholes



July 4, 1944. G, HASSLER 2,352,834

METHOD OF AND MEANS FOR ADJUSTING FLOW RATES OF FLUIDS THROUGHFORMATIONS TRAVERSED BY BOREHOLES Filed May 9, 1942 2 Sheets-Sheet 2 9|]30 87 85 90 3 v 92 gg El 6 ,.f/

G) G) @D I, F QII E i w x x x x x x if; 0 0 C 'A" A x x x x x l o C C Iit, x x x x x ...'i -f i v s x x x x x x s I O D C y C 1'. B x x x x x x.lj o o o o X X X X X X x Producing wen T O njzdon well faknq .0. Toomuch wczrer @mmm-@MM Patented July 4, 1944 METHOD OF AND MEANS FORADJUSTING FLOW RATES OF FLUIDS THROUGH FOR- MATIONS TRAVERSED BYBOREHOLES GeralfLL. Hassler, Berkeley, Calif., assigner to ShellDevelopment Company, San Francisco, Calif., a corporation of DelawareApplication May 9, 1942, Serial No. 442,378

7 Claims.

The present invention relates to methods of drilling and producing oiland gas wells and pertains more particularly to methods of determiningthe properties of formations traversed by a borehole. i

Generally, in oil wells, the strata traversed by the borehole varyconsiderably in their ability t conduct fluid therethrough. Thisdifference in permeability of the various strata gives rise toconsiderable diiliculties, particularly in repressuring or floodingsystems for secondary recovery of depleted oil Isands wherein a.complete or uniform recovery from the various oil-bearing strata cannotbe obtained, since a high rate of recovery of oil is effected from thehighly permeable strata while a low recovery is attained in the lesspermeable regions. This condition occurs when repressuring isindiscriminate, as when the flooding fluid, such as air, gas, or water,is forced into a formation from a .pressure well without regulation ofthe pressure, volume, and velocity as between strata of dierentpermeabilities.

To overcome these diflculties, heretofore it has been proposed to placein the injection well of such systems a tubular sleeve Withspaced ringsof openings of various sizes and with means to seal off ythe spaceoutside the sleeve between the rings of openings, whereby the flow offluid into the various strata is controlled by the size of openingcommunicating with the strata opposite said opening. However, thisdevice is unsatisfactory in that permeability measurements must first bemade, then a special sleeve constructed to correspond to saidmeasurements and flow rate calculations, and subsequently the sleeveY 'apermeability-measuring device without the use of expensive andcumbersome electrical cables.

It is also an object of this invention to provide means to measure theeffective permeabilities of strata traversed by a borehole and toregulate the amount of flooding iluid taken by the strata to the desiredvalues without the necessity of extremely accurate correlation ofpermeability measurements with depth and location of liner sleeves orthe like.

It is a further object of this invention to provide surface controlmeans, whereby signals can be transmitted through the mud fluid, drillpipe, or walls of the borehole, for actuating permeability-measuringinstrument in a well borehole.

It is still another object of this invention to provide a device foradjusting the effective permeabilities or flow resistances of thedesired porous formations in an injection well of a waterflooding systemtoward a more nearly uniform medium value, whereby ooding water willpass into the various formations at substantially the same rate.

It is also an object of this invention to provide a method and apparatusfor isolating a stratum traversed by a well from the rest of theborehole, flowing a liquid into said stratum., measuring the liquid owrate at a point close to the point of injection into the stratum, andtransmitting the measurement to the well surface by means of vibrationsignals.

It is a still further object of the present invention to provide meansfor measuring the rate of flow of a liquid into a stratum traversed by awell borehole, and, depending on the measured rate of liquid flow,either decreasing its effective permeability by partially plugging saidstratum with finely divided inert material, or increasing its effectivepermeability by means or" acid in order to obtain a predetermined rateof liquid now into said stratum.

Other objects will be readily apparent from the following description,taken in reference, to the drawings, wherein:

Figure I is a longitudinal sectional view of the upper portion of apreferred embodiment of a device used to carry out the presentinvention, showing said device in operative position in a borehole.

Figure II is a continuation of Figure I, showing the lower portion ofsaid device.

Figure III is a cross-sectional view taken along the line III-III ofFigure I.

Figure IV is a schematic vertical sectional view of an oil well with thepresent device positioned therein.

Figure V is a diagrammatic view of a water ood lease map showing asection of the oil field before treatment and a section after treatmentaccording to the present invention.

Generally, the present invention resides in isclating or packing ofi astratum traversed by a -we1l from the rest'of the borehole, for example,

Packed-olf space in the borehole, wherein its rate of eiilux may bemeasured.

Since the present invention is particularly ap- 4 plicable to theregulation of the ow of ooding or repressuring fluid through the variousstrata of an injection well of a flooding or repressuring system, itwill be described in relation thereto.

After the effective permeability or flow resistance of a stratum in aninjection well has been measured, the walls of the borehole in thatstratum are suitably treated to adjust the uid flow rate to the desiredvalue by flowing into the stratum together with the fluid either apermeability decreasing or plugging material, such as a finely divided,preferably acid-soluble, solid, e. g. chalk, oyster shells, etc., or apermeability increasing material such as an acid capable of formingWater-soluble salts with the earth formation, for example, hydrochloricor hydrobromic acids, solvents, for example pyridine or nitrogen bases,etc.

The permeability measurements are preferably indicated at the surfaceand the control of the expansion of the packers and injection of theplugging material or acid are eected by means of signals or vibrations,such as sound waves or 'the like, transmitted through the drill stem,the

borehole walls or fluid filling the well, or other wave transmissionpaths available in the well. However, if desired, insulated electriccables may be used in whole or in part to effect such measurement ofcontrol communications.

I Referring to Figures I, II and III of the drawings, a preferredembodiment of a device for carrying out these operations is contained ina tubular housing I I (Figure IV) which may be formed of coupledsections Ila, I Ib, llc, and Ild. The lower section IIa, as shown inFigure II, is pref- A erablyformed with a tapered lower end I2 and oftwo tubular housing sections IIb and llc, and

extending therethrough is a tubular member or pipe 20. End plates 22 and23 and intermediate plate 2I, Which also acts as a coupling for thehousing sections IIb and llc, surround the pipe 20 and divide theannular space thereabout into two tanks 24 and 25, which may be filledwith chalk suspension and acid, respectively, by means of filler plugs26 and 21. The tanks 24 and 25 are I l respectively provided with ports28a and 28h in their'upper portion and ports 29a and 29h in their lowerportion, which ports communicate with the central channel through pipe20. A tubular element 30 is reciprocable coaxially in the central pipe20 and carries valve members 3Ia,

actas lib, 3Ic and 3Id which normally close the ports 28a, 29h and 29aand 29h in tanks 24 and 25. Stops 50 within the pipe 20 andribs v5I onthe tubular element 30 limit the reciprocation of said element 30. Aflexible 'conduit 59 attached to the lower end of the tubular element 30communicates with the interior of the'inflatable packers I6.

Preferably directly above the upper end plate 22 of the tank 24 isa"chamber 32 which contains a suitable flowmeter 33, shown also inFigure HI. A conduit 34 supplies fuid to the flowmeter 33 from theoutside of the housing Ilcv and a second conduit 35 communicates withthe centra1 pipe 20 for discharging thereinto iiuid from the owmeter 33,which thereby is adapted to measure the fluid fiow into the centra1 pipe20. The owmeter 33 is also adapted to actuate an impulse sender and may,for example, be of the common water meter or rotary piston type, whichcomprises, as shown more fully in Figure III, an eccentric cylindricalrotor 36 and a reciprocable slide barrier 31 arranged to be forcedagainst the rotor 36 by resilient means, such as a spring 39, acting onthe outer end of the slide 31, which is positioned between the inlet andoutlet conduits 34 and 35. Fluid entering the space between the rotor 36and the owmeter housing 33 from the inlet conduit 34 on one side oi thebarrier 31 and passing to the outlet' conduit 35 on the other side ofthe barrier 31 causes the eccentric rotor 36 to rotate. Thereciprocation of the barrier or slide 31 caused by the rotation of theeccentric ,rotor 36 cyclically operates an impulse sender switch or aclicker, in any suitable manner, such as by closing the electricalcircuit through contact 36 and spring 39, to which are attachedelectrical conductors leading to the sending apparatus to besubsequently described.

The upper end of the reciprocable tubular element 30 extends throughchamber 32 and flowmeter 33 therein and through a packing gland 40 intoa motor chamber 4I. Any suitable arrangement of power means may beprovided in this chamber 4I for reciprocating at will the valve-carryingtubular element 30 and for pumping uid into the expansible packers I5through tubular element 30 and exible conduit 59. For example, thetubular element 30 may be recipro-v cated by means of' an electric motor45 which rotates a Worm gear 46 engaging a gear' 41 which rotates a gear46 engaging a rack 49 carried. on the upper end portion of the tubularelement 30. A second electric motor 55 operates a pump 56 having anintake 51 communicating with the outside f the housing II. The pump 56discharges into a flexible conduit 58 which connects to the upper end ofthe reciprocable tubular element 30.

The upper housing section I Id provides a water tight compartment forbatteries 65, a relay set 66, signal-receiving means, such as a soundreceiving cone 61, and signal-transmitting means, such as a transmittercone or horn 68. The relay set 66, which may comprise suitableamplifying means, is adapted to yactuate the pump motor. 55 andvalve-operating motor 45 in response to predetermined signalstransmitted from the surface to the receiving cone 61. For this purpose,any suitable type relay system 66 may be used, and may comprise forexample, an impulse-activated system such as is used in dial telephonesystems or a magnet system which will set up or generate a current whena diaphragm vibrates, as described, for example, in

or through a suitable amplifying system. The

assaasa current actuating impulses may be of low frequency so as not toVinterfere with or to be actuated by the signal or impulse output of thetransmitting cone 88 which may operate on a high frequency. I1 desired,the relay set 68 may comprise several tuned frequency circuits and thusbe actuated by signals or vibration of different frequencies in awell-known manner, such, for example, as described in thev Mattingly etal. Patent No. 2,255,721, while the transmitting cone 83 which reportsthe ilow rate, may be operated at still other frequencies.

At the surface there may be provided suitable equipment, such as, forexample, a portable unit mounted on a truck 85, as shown in Figure IV.The truck 85 may carry a small derrick 85, a

l drum 81 for the wire line 16, a vibration or sound transmitter 88 andreceiver 88, together with amplifying and filter circuits and aninstrument control board 90, and supply tanks 9| for acid and chalksuspension. Likewise, it is preferable to provide some means, such as apump 82 which may be located at the well head for high pressure`injection of flooding fluid, such as water, during the period oftreatment.

In operation of the preferred embodiment of this invention, theassembled device comprising the housing Il is lowered to the bottom of aborehole by means of a wire line 16, derrick 86, drum 81, etc. When thedevice reaches the desired depth, a particular sound, vibration, impulseor a series of impulses is initiated at the surface by means of thetransmitting device 88, which travels down through the medium lling theborehole or the walls of the borehole, etc., to the receiving cone 61,and is conducted thereby to the relay set68. In response to thisparticular signal, the relay set 66 selectively actuates the pump motor55 and pump 56 in a predetermined manner, depending on the nature of thesignal.

' On a first signal, fluid from the borehole is caused to be forced bythe pump 56 through conduit 58, the tubular element and the conduit 59and thence into the packers I5, which are thereby expanded against theborehole walls to seal olf or isolate a portion of the borehole.

The flooding or repressuring fluid, such as. for example, water, air,gas, etc., is injected into the borehole under high pressure by pump 82and the main portion thereof flows down around the housing- Il andthrough the by-pass channel I3 and into the formation but not into thatportion isolated between the expanded packers l5. A small portion ofthis flooding uid ilows through the conduit 34 into the flowmeter 33 andout through conduit 35 into the annular space between the tubularelement 38 and the walls of the central pipe 20, and thence down intothe housing member Ila and out through the perforations I4 into theformation sealed off betweenthe packers I5.

It will be seen that there is only a small pressure difference acrosseach packer, since the pressure of the flooding fiuid in the spacebetween the packers is only slightly lower than the pressure above andbelow the pair of packers by the amount of the resistance of theilowmeter and conducting tube 20. It is therefore only necessary toapply suiiicient pressure to the flooding water to cause the operationof the flowmeter 33 and the chemical tanks 24 and 25.

The rate of flow of fluid into the sealed-ofi.'

zone is measured by the flowmeter 33 and the reciprocation of thedividing barrier 31 due to the rotation of the eccentric rotor 38 causesthe horn or transmitter cone 88 to be actuated periodically. If desired,instead, the reciprocation of the barrier 31 may be arranged to produceclicks which can be amplified and conducted to the-transmitter cone 88.The series of actuatins of the horn or transmitter cone 68, as can be.noted at the surface by receiver 89 and control board Il, will be fastif the zone is so permeable that it takes much fluid, or will be slow ifthe Zone takes a small amount of fluid.

In the case where the flow is too great, the operator sounds anothernote or signal of particular frequency into the borehole, which causesthe relay set 68 to energize the valve-operating motor 45 in the properdirection for moving the slidable tubular element 38 and valves 3lupwards into a position opening the ports 28a and 29a of the upperchalk-containing tank 24; the flow in the central channel 20 is therebytemporarily partially diverted through the chalk tank 24. By thus addingsmall increments of chalk to the fluid flowing to the sealed-off orisolated strata so as to build up a thin mud cake, and by continuallyobserving at the surface the flow rate as reported by the iiowmeter 33and transmitter 88, the operator can adjust (that is, in this case,restrict) the ow rate to a desired medium value. After enough chalksuspension has been added to the stream of fluid to obtain the desiredrestricted flow rate into this stratum, another note is sounded at thesurface to .cause the motor 45 to return the valve-carrying element 30to neutral position.

In the case where the flow is-too small, that is, less than apredetermined medium rate, the operator initiates another particularsignal by transmitter 88 at the surface, which signal on travelling downthrough the borehole and impinging on the receiving cone 61 causes therelay set 88 to energize the valve-operating motor 45 in the properdirection for moving the slidable tubular element 38 and valves 3ldownwards into a position opening the ports 28h and 29h of the loweracid-carrying tank 25. The iiow of flooding water or other uid throughthe central channel 20 is thereby temporarily partially diverted intothe acid tank 25. A slidable annular separator or spacer above the acidin the acid tank 25 is preferably provided to prevent the water enteringthe upper port 28h from diluting the acid. The acid thus added to theflooding water passes into the section of the formation being tested andincreases its permeability, allowing greater fluid flow thereinto.Preferably, the ports 28h and 28h are opened for short periods by firstsounding a signal causing the valvecarrying element 30 to move downwardand then closely thereafter sounding a signal causing the element 30 tomove back to a neutral position. These signals may be repeated untilenough small increments of acid are thereby injected into this isolatedformation to increase the flow rate to the desired medium value whilethe flow rate is being continually measured and reported to the surfaceby the flowmeter 33 and transmitting cone or horn 68.

The packers I5 are then deflated by stopping or reversing the pump 55,which is accomplished by the relay set 5G in response to a particularnote or set of Vsignals issued by surface transmitter 88, andthe deviceraised up to a position opposite the next higher stratum or section ofthe borehole. The above operation of setting the packers l5 anddeterminingthe rate of now of liquid into the formation between thepackers I5 are repeated and thereafter the proper treatment with acid orchalk is applied, depending upon the permeability of this section of theborehole as measured and reported to the surfield, the treatment of theinjectionwells in the above manner results in each injection Well takinga balanced share of the flooding water, which desirable condition isrepresented by the uniformity of the dots signifying injection wells inthe lower treated portion B as contrasted to the non-uniformity of theupper untreated portion A of the water flood lease map shown in FigureV.

It is readily apparent that various changes and modifications can bemade in the abovedescribed method and apparatus Without departing fromthe spirit of the invention, one essential feature of which is the stepof measuring the rate of ow of fluid through a porous formationtraversed by a borehole at a point closely adjacent to said porousformation. Thus, for example, if desired, instead of controlling theabovedescribed device by means of vibration or sound impulsestransmitted through the medium filling the borehole. communication andcontrol may be partially or completely accomplished directly by means ofa cable containing insulated electrical conductors. Also. the presentinvention may be applied to other than injection wells of oodingsystems. Thus, for example, the rate of flow of liquid .from/ porousformations traversed by a borehole may be measured by placing expansiblepackers, a suitable owmeter and reporting system, such as in theabove-described flow adjusting device, at a position in the boreholewith the flowrneter closely adjacent the' point of efflux of fluid fromthe formation sealed off from the rest of the borehole between the twoexpansible packers.

I claim as my invention:

l. A method for substantially equalizing fluid flow into the variousporous strata trayersed by an open borehole of uid injection wells ofooding or repressuring systems, comprising successively applying toportions of the borehole the treatment comprising the steps of4 packingoff a desired vertical portion of the borehole, forcing a uid into theborehole walls surrounding said portion, measuring the rate ,of saidflow at a point adjacent said portion, indicating at the surface of thewell said measured flow rate, and

lstantially equalized.

2. In a device for adjusting the rate of fluid flow into the variousstrata traversed by an injection well of a flooding system, a housingadapted to be lowered into a borehole, a pair of tion traversed by theborehole, passage means in said housing opening outwardly above andbetween the packer means for directing fluid ow into said packed-offsection of the formation, meter means in said passage means formeasuring the ow of fluid therethrough, a reservoir in said housingcontaining a comminuted inert material, a second reservoir in saidhousing containing an acidic material capable of forming water-solublesalts with the earth formation,

said reservoirs having openings communicating with vsaid passage means,valve means closing said openings from said reservoirs to said passagemeans, and controlmeans operablefrom the surface for actuating saidvalve means to open and close said openings for selectively adding thecontents of one of said reservoirs to the fluid flowing into saidformation.

j 3. In a device for adjusting the rate of fluid flow into the variousstrata traversed by an injection well of a flooding system, a housingadapted to be lowered into a borehole, a pair of axially spacedexpansible packer means mounted therein for packing oi a section of theformation traversed by the borehole, channel means in said 1 housingopening above and below the packer means and adapted to allow the mainportion of duid flowing down through the borehole to bypass saidpacked-off portion, passage means in said housing opening outwardlyabove and between the packer means and adapted to cirect a smallerportion of the iiuid flow into said packedoff section of the formation,meter means in said passage means for measuring the ow of uidtherethrough and means for adjusting the flow characteristics of saidformation comprising a reservoir in said housing containing a comminutedinert material, a second reservoir in said housing containing an acidicmaterial capable of forming water-soluble salts with the earthformation, said reservoirs having openings communicating with saidpassage means, and means controlling the opening and closingof saidopenings for selectively adding the contents of one of said reservoirsto the uid flow into said formation.

4. In a device for adjusting the rate of fluid ow into the variousstrata traversed byv an injection well of a ooding system, a housingadapted to be lowered into a borehole, a pair of axially spacedexpansible packer means mounted therein for packing olf a section of theformation traversed by the borehole, channel'means 'in' said housingopening above and below the well, and means for adjusting the owcharacteristics of said formation comprising a reservoir in said housingcontaining a comminuted inert y material, a second reservoir in saidhousing containing an acidic material capable of forming water-solublesalts with the earth formation, said reservoirs having openingscommunicating with said passage means, and means controlling the openingand closing of said openings for selec` tively adding the contents ofone of said reservoirs to the fluid owing into said formation.

5. In anv apparatus for treating formations traversed by a borehole ahousing adapted to be lowered into the borehole, at least two expansiblepackers vertically spaced from each other carried by said housing, meansfor expanding said packers into contact with the walls of the borehole,whereby a portion thereof is sealed oilr by said packers, passage meansin said housing opening outwardly above and between the packer means andadapted to direct fluid flow into the sealedoiI portion of the boreholebetween said packers, metering means in said passage for measuring saidflow, means for conveying the indications of said metering means to thesurface, a reservoir in said housing containing a substance capable ofmodifying the resistance to fluid flow through the formation, saidreservoir having an opening communicating with said passage means. andmeans controlling the opening and closing of said opening for injectingsaid substance into the borehole between said packers.

6. In an apparatus for treating formations traversed by a borehole, ahousing adapted to be lowered into the borehole, at least two expansiblef packers vertically spaced from each other carried by said housing,means for expanding said packers into ,contact with the walls of theborehole, whereby a portion thereof is sealed oir by said packers,passage means in said housing opening outwardly above and between thepacker means and adapted to direct uid iiow into the sealed-oil. portionoi' the borehole between said packers, metering means in said passagefor measuring said flow, means for conveying the indications of saidmetering means to the surface, a reservoir in said housing containing asubstance capable of modifying the permeability of the borehole walls,said reservoir having an opening communicating with the passage means,valve means closing said opening from the reservoir to said passagemeans, and relay means actuated by an impulse transmitted from thesurface for opening and closing said valve means to control the flow ofpermeability modifying substance through the opening in said reservoirto the sealed-off portion of the borehole packers.

7. A method for substantially equalizing fluid flow into the various'porous strata traversed by an open borehole, comprising successivelyapplying to portions of the borehole the treatment comprising the stepsof packing oif a desired vertical portion of the borehole, forcing afluid into the borehole walls surrounding said portion, measuring therate of said ow at a point adjacent said portion, indicating at thesurface of the well said measured flow rate, and while maintaining saidvertical portion packed off changing said flow rate by injecting intosaid portion of the borehole a iiuid comprising' a substance capable ofmodifying the resistance to fluid flo'w through the formation to apredetermined value whereby the resistances to fluid iiow of thevarious, portions of the borehole are substantially equalized.

GERALD L. HASSLER.

between, said

